A coupler for a hoist can engage an anchor bolt having a shaft and a connecting bolt head, this anchor bolt being embedded in the precast concrete part, e.g. a prefabricated panel, and a spherically shaped connecting hook member engageable with the anchor bolt and from which an operating lever projects and which has a directly or indirectly pivotally connected suspension shackle connected to the hoist. The spherically shaped hook member has a circular slot which fits the connecting bolt head and is provided at one end with an entrance opening through which the bolt head of the anchor bolt embedded in the concrete can be inserted.
In a known coupler of this type, as taught in German Patent No. 12 280 the connecting hook member, when seen in a view orthogonal to the plane of the slot, is a completely spherical component with an operating arm or lever extending from it.
At the center of this completely spherical component a hole receives the suspension shackle which is suspended with its pivot eye pivotally connected therewith.
The hole runs perpendicular to the plane of the slot. The structure and arrangement of the components is such that the connecting bolt head of the anchor bolt embedded in concrete is guided into the entrance opening of the connecting hook member when its operating lever is approximately horizontal and rests on the prefabricated concrete body. The operating lever or arm is pivotable from this entering position through about 180.degree. into a locking position.
The suspension shackle is constructed as a bridging shackle, whose bridge member separates a pivot eye from a suspension eye. In taking the load the suspension shackle by way of the bridging member engages the operating lever to ensure that the connecting hook member will be in the locked position.
Kinematically the process is reversed on releasing the concrete body. While this arrangement has been successfully used we have found that for simpler fabrication, more convenient operations, and improved reliability, some modification of the structure is highly desirable.